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Abstract:

Provided are a vibration isolating table (1) with damping mechanism
having initial rigidity so that a vibration isolation subject is not
swayed under a state in which no vibrations act, and configured to
function in a case where vibrations act so that the vibration isolation
subject can be protected, and a vibration isolating table unit (15) using
the vibration isolating table (1). The vibration isolating table includes
a fixed plate (2); a guiding member (42) provided so as to be freely
movable in an X direction relative to the fixed plate (2); a movable
plate (3) provided so as to be freely movable relative to the guiding
member (42) in a Y direction orthogonal to the X direction; an
X-directional circulation belt (6) configured to circulate in accordance
with X-directional movement of the guiding member (42) relative to the
fixed plate (2); a Y-directional circulation belt (9) configured to
circulate in accordance with Y-directional movement of the movable plate
(3) relative to the guiding member (42); and rotary dampers (7, 10)
respectively provided to the fixed plate (2) and the movable plate (3),
and respectively including rotationally driven members (70, 100) around
which the X-directional circulation belt (6) and the Y-directional
circulation belt (9) are respectively looped, the rotary dampers (7, 10)
being configured to respectively impart resistance to rotational motion
of the rotationally driven members (70, 100).

Claims:

1.-3. (canceled)

4. A vibration isolating table with damping mechanism, comprising: a
fixed plate having four corner portions to be formed into a substantially
rectangular shape, the four corner portions including a pair of opposing
corner portions defining a diagonal line that matches with an X
direction, and another pair of opposing corner portions defining another
diagonal line that matches with a Y direction orthogonal to the X
direction; a guiding member provided so as to be freely movable in the X
direction relative to the fixed plate; a movable plate on which a
vibration isolation subject is to be placed, the movable plate having
four corner portions to be formed into a substantially rectangular shape,
the movable plate being provided so as to be freely movable relative to
the guiding member in the Y direction, and freely movable within a plane
parallel to the fixed plate; a plurality of elastic members provided
between the fixed plate and the guiding member, the plurality of elastic
members being configured to pull the movable plate shifted relative to
the fixed plate back to an initial position; a plurality of elastic
members provided between the movable plate and the guiding member, the
plurality of elastic members being configured to pull the movable plate
shifted relative to the fixed plate back to the initial position; rotary
dampers arranged at the another pair of opposing corner portions of the
fixed plate situated on the another diagonal line that matches with the Y
direction; rotary dampers arranged at a pair of corner portions of the
movable plate situated on the diagonal line that matches with the X
direction; X-directional circulation belts looped around rotationally
driven members provided to the rotary dampers of the fixed plate, and
stretched into a circular shape along a predetermined path including a
route parallel to the diagonal line of the fixed plate that matches with
the X direction, the X-directional circulation belts being configured to
circulate in accordance with X-directional movement of the guiding member
relative to the fixed plate; and Y-directional circulation belts looped
around rotationally driven members provided to the rotary dampers of the
movable plate, and stretched into a circular shape along a predetermined
path including a route parallel to the another diagonal line of the
movable plate that matches with the Y direction, the Y-directional
circulation belts being configured to circulate in accordance with
Y-directional movement of the movable plate relative to the guiding
member.

5. The vibration isolating table with damping mechanism according to
claim 4, wherein the X-directional circulation belts, the Y-directional
circulation belts, the rotary dampers of the fixed plate, and the rotary
dampers of the movable plate are housed in a gap between the fixed plate
and the movable plate that are overlaid one on top of another through the
intermediation of the guiding member.

6. The vibration isolating table with damping mechanism according to
claim 4, wherein the plurality of elastic members of the fixed plate are
coupled to the fixed plate at a position on an inner side of the
predetermined path of the X-directional circulation belts, and the
plurality of elastic members of the movable plate are coupled to the
movable plate at a position on an inner side of the predetermined path of
the Y-directional circulation belts.

7. The vibration isolating table with damping mechanism according to
claim 4, wherein the plurality of elastic members of the fixed plate are
provided between the guiding member and the another pair of opposing
corner portions of the fixed plate at which the rotary dampers of the
fixed plate are arranged, and the plurality of elastic members of the
movable plate are provided between the guiding member and the pair of
corner portions of the movable plate at which the rotary dampers of the
movable plate are arranged.

8. A vibration isolating table unit, comprising: the vibration isolating
table with damping mechanism according to claim 4; and a vibration
isolating table with inertial mass to be used in a state of being coupled
to the vibration isolating table with damping mechanism, wherein the
vibration isolating table with inertial mass comprises an inertial mass
provided in place of the rotary dampers of the vibration isolating table
with damping mechanism.

9. The vibration isolating table with damping mechanism according to
claim 5, wherein the plurality of elastic members of the fixed plate are
coupled to the fixed plate at a position on an inner side of the
predetermined path of the X-directional circulation belts, and the
plurality of elastic members of the movable plate are coupled to the
movable plate at a position on an inner side of the predetermined path of
the Y-directional circulation belts.

10. The vibration isolating table with damping mechanism according to
claim 5, wherein the plurality of elastic members of the fixed plate are
provided between the guiding member and the another pair of opposing
corner portions of the fixed plate at which the rotary dampers of the
fixed plate are arranged, and the plurality of elastic members of the
movable plate are provided between the guiding member and the pair of
corner portions of the movable plate at which the rotary dampers of the
movable plate are arranged.

11. The vibration isolating table with damping mechanism according to
claim 6, wherein the plurality of elastic members of the fixed plate are
provided between the guiding member and the another pair of opposing
corner portions of the fixed plate at which the rotary dampers of the
fixed plate are arranged, and the plurality of elastic members of the
movable plate are provided between the guiding member and the pair of
corner portions of the movable plate at which the rotary dampers of the
movable plate are arranged.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a vibration isolating table with
damping mechanism, which is interposed between vibration isolation
subjects such as a precision apparatus, an electronic apparatus, and an
art object and a floor surface of a building, and to be used for the
purpose of protecting the vibration isolation subjects from external
vibrations such as an earthquake, and to a vibration isolating table unit
using the vibration isolating table.

BACKGROUND ART

[0002] Conventionally, as a measure against vibrations to be caused when
transporting vibration isolation subjects such as a precision apparatus,
an electronic apparatus, and an art object, or as a measure against
external vibrations such as an earthquake in a case where the vibration
isolation subjects are placed in a building, a vibration isolating table
has been used for the purpose of isolating those vibration isolation
subjects from vibrations of a floor surface.

[0003] As such type of vibration isolating table, the vibration isolating
table disclosed in JP 2000-240719 A is known. This vibration isolating
table is a two-dimensional vibration isolating table including a
Y-directional vibration isolating part and an X-directional vibration
isolating part which are overlaid one on top of the other relative to the
floor surface. The topmost placement table part is freely movable in the
X direction and the Y direction relative to the floor surface.

[0004] The Y-directional vibration isolating part includes a guiding
member fixed to the floor surface, a Y-directional rail that is held so
as to be freely movable in the Y direction by the guiding member and is
fixed to an intermediate plate, and a plurality of elastic members
provided between the intermediate plate and the floor surface so as to
hold the intermediate plate at the initial position on the floor surface.
Further, the X-directional vibration isolating part includes a guiding
member fixed to the intermediate plate of the Y-directional vibration
isolating part, an X-directional rail that is held so as to be freely
movable in the X direction by the guiding member and is fixed to the
placement table part, and a plurality of elastic members provided between
the placement table part and the intermediate plate so as to hold the
placement table part at the initial position on the intermediate plate.

[0005] In the vibration isolating table structured as described above, in
a case where vibrations act on the floor surface, the Y-directional
vibration isolating part and the X-directional vibration isolating part
interact with each other to isolate, from the vibrations of the floor
surface, the placement table part on which a vibration isolation subject
is placed, and the cycle of the vibrations of the placement table part is
set sufficiently long, with the result that the sway of the vibration
isolation subject can be suppressed. Further, when the vibrations of the
floor surface cease and the vibrations of the placement table part also
cease, the placement table part is pulled back to the initial position
due to the tensile force of the elastic members.

[0006] Further, the conventional vibration isolating table is provided
with a damping mechanism for quickly ceasing the vibrations of the
placement table part. The damping mechanism is provided both to the
Y-directional vibration isolating part and to the X-directional vibration
isolating part. The damping mechanism of the Y-directional vibration
isolating part includes a frictional member that is opposed to the side
surfaces of the Y-directional rail through the intermediation of small
gaps and is held so as to be freely rotatable relative to the floor
surface, and each of the elastic members is stretched between one end of
the frictional member and the intermediate plate. The damping mechanism
of the X-directional vibration isolating part has a similar structure,
that is, the damping mechanism of the X-directional vibration isolating
part includes a frictional member that is opposed to the side surfaces of
the X-directional rail through the intermediation of small gaps and is
held so as to be freely rotatable relative to the intermediate plate, and
each of the elastic members is stretched between one end of the
frictional member and the placement table part.

[0007] In the damping mechanism structured as described above, when the
intermediate plate moves in the Y direction relative to the floor surface
or when the placement table part moves in the X direction relative to the
intermediate plate, the frictional member rotates due to the tensile
force of the elastic members so that the frictional member is brought
into press contact with the Y-directional rail or the X-directional rail.
As a result, a frictional resistance force is generated. As the distance
of movement of the intermediate plate relative to the floor surface
becomes larger or as the distance of movement of the placement table part
relative to the intermediate plate becomes larger, the elastic members
exert a larger tensile force, and hence the frictional resistance force
generated between the frictional member and each rail also becomes
larger.

[0008] In other words, in the vibration isolating table disclosed in JP
2000-240719 A, as the placement table part moves farther away from the
initial position, a larger damping force acts on the vibrations of the
placement table part.

CITATION LIST

Patent Literature

[0009] Patent Literature 1: JP 2000-240719 A

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

[0010] However, in the above-mentioned conventional vibration isolating
table with damping mechanism, for example, under a state in which
vibrations do not act from the floor surface onto the vibration isolation
subject and the placement table part is set at the initial position in
the X direction and also in the Y direction, the frictional member is not
brought into press contact with both the X-directional rail and the
Y-directional rail, and hence no frictional resistance force acts between
the frictional member and each rail. Therefore, the rigidity of the
placement table part situated at the initial position is insufficient,
and hence the placement table part moves relative to the floor surface
even when the floor surface slightly vibrates, which leads to an
inconvenience that the vibration isolation subject is easily swayed
relative to the floor surface.

Means for Solving the Problems

[0011] The present invention has been made in view of the above-mentioned
problem, and it is therefore an object of the present invention to
provide a vibration isolating table with damping mechanism having initial
rigidity so that a vibration isolation subject is not swayed under a
state in which no vibrations act, and configured to function reliably in
a case where large vibrations such as an earthquake act so that the
vibration isolation subject can be protected, and to provide a vibration
isolating table unit using the vibration isolating table.

[0012] In order to achieve the above-mentioned object, the present
invention provides a vibration isolating table with damping mechanism,
including: a fixed plate; a guiding member provided so as to be freely
movable in an X direction relative to the fixed plate; a movable plate on
which a vibration isolation subject is to be placed, the movable plate
being provided so as to be freely movable relative to the guiding member
in a Y direction orthogonal to the X direction, and freely movable within
a plane parallel to the fixed plate; a plurality of elastic members
provided between the fixed plate and the guiding member and between the
movable plate and the guiding member, the plurality of elastic members
being configured to pull the movable plate shifted relative to the fixed
plate back to an initial position; an X-directional circulation belt
stretched on the fixed plate into a circular shape along a predetermined
path, the X-directional circulation belt being configured to circulate in
accordance with X-directional movement of the guiding member relative to
the fixed plate; a Y-directional circulation belt stretched on the
movable plate into a circular shape along a predetermined path, the
Y-directional circulation belt being configured to circulate in
accordance with Y-directional movement of the movable plate relative to
the guiding member; rotary dampers respectively provided to the fixed
plate and the movable plate, and respectively including rotationally
driven members around which the X-directional circulation belt and the
Y-directional circulation belt are respectively looped, the rotary
dampers being configured to respectively impart resistance to rotational
motion of the rotationally driven members.

Effects of the Invention

[0013] In the above-mentioned vibration isolating table with damping
mechanism according to the present invention, the movable plate is freely
movable in the X direction and in the Y direction relative to the fixed
plate through the intermediation of the guiding member. When vibrations
such as an earthquake act on the fixed plate, the movable plate may
vibrate irrespective of the vibrations acting on the fixed plate, and the
vibration isolation subject placed on the movable plate can be isolated
from the vibrations acting on the fixed plate. At this time, when the
movable plate moves in the X direction and in the Y direction relative to
the fixed plate, the X-directional circulation belt and the Y-directional
circulation belt circulate in accordance with the movement in the
predetermined path along which the X-directional circulation belt and the
Y-directional circulation belt are stretched, to thereby transmit the
rotational motion to the rotationally driven members provided to the
rotary dampers. The rotary dampers impart the resistance to the
rotational motion of the rotationally driven members, and thus the
X-directional and Y-directional vibrations of the movable plate are
damped.

[0014] The rotary dampers impart the resistance to the rotational motion
of the rotationally driven members, and hence, under a state in which the
movable plate is set at the initial position without vibrating relative
to the fixed plate, the rotary dampers impart initial rigidity to the
movable plate. Therefore, it is possible to prevent the sway of the
movable plate relative to the fixed plate as long as large vibration
energy is not input due to an earthquake or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] [FIG. 1] A partial sectional front view illustrating an example of
an embodiment of a vibration isolating table with damping mechanism to
which the present invention is applied.

[0016] [FIG. 2] A plan view illustrating a structure on a fixed plate side
of the vibration isolating table with damping mechanism illustrated in
FIG. 1.

[0017] [FIG. 3] A plan view illustrating a state of the fixed plate side
of the vibration isolating table with damping mechanism illustrated in
FIG. 1 at the time when the vibration isolating table is operating.

[0018] [FIG. 4] A plan view illustrating an example of an embodiment of a
vibration isolating table with inertial mass to be used in combination
with the vibration isolating table with damping mechanism illustrated in
FIG. 1.

[0019] [FIG. 5] A plan view illustrating an example of a structure on the
fixed plate side of a vibration isolating table unit constructed of the
vibration isolating table with damping mechanism illustrated in FIG. 2
and the vibration isolating table with inertial mass illustrated in FIG.
4 which are coupled to each other.

[0021] Hereinafter, referring to the accompanying drawings, detailed
description is given of a vibration isolating table with damping
mechanism and a vibration isolating table unit using the vibration
isolating table according to the present invention.

[0022]FIG. 1 is a sectional front view illustrating an example of a
vibration isolating table 1 with damping mechanism to which the present
invention is applied. The vibration isolating table 1 with damping
mechanism (hereinafter, referred to as "dumping vibration isolating table
1") includes a fixed plate 2 to be installed on the floor surface, a
movable plate 3 on which a vibration isolation subject requiring
vibration isolation is to be placed, the vibration isolation subject
being typified by a precision apparatus, an electronic apparatus, and an
art object, and a two-dimensional guiding mechanism 4 for freely moving
the movable plate 3 relative to the fixed plate 2 in an X direction and a
Y direction (direction toward the back side of the drawing sheet of FIG.
1) orthogonal to the X direction. Note that, the example of application
of the present invention is not limited to the dumping vibration
isolating table 1 illustrated in FIG. 1.

[0023] The two-dimensional guiding mechanism 4 includes a lower guiding
rail 40 laid on the fixed plate 2 along the X direction, an upper guiding
rail 41 fixed to the movable plate 3 on its lower surface side along the
Y direction, and a guiding member 42 that takes motion along both the
lower guiding rail 40 and the upper guiding rail 41. Further, the guiding
member 42 includes a lower slidable block 43 mounted onto the lower
guiding rail 40 through the intermediation of a large number of rolling
elements, an upper slidable block 44 mounted onto the upper guiding rail
41 through the intermediation of a large number of rolling elements, and
a coupling plate 45 having the slidable blocks 43 and 44 fixed to the
front and back surfaces thereof.

[0024] As a combination of the lower guiding rail 40 and the lower
slidable block 43 and a combination of the upper guiding rail 41 and the
upper slidable block 44, a commercial linear guiding device may be used.
For example, the linear guiding device includes a large number of rolling
elements, a guiding rail having a rolling surface for the rolling
elements formed along a longitudinal direction thereof, and a slidable
block having an infinite circulation path for the rolling elements and
mounted so as to be freely movable along the guiding rail. From the
viewpoint of preventing separation of the movable plate 3 from the fixed
plate 2, it is desired that the slidable blocks 43 and 44 can
respectively receive any loads acting on the planes orthogonal to the
longitudinal directions of the guiding rails 40 and 41 under a state in
which the slidable blocks 43 and 44 are respectively mounted onto the
guiding rails 40 and 41. Further, the load capacity of each of the lower
slidable block 43 and the upper slidable block 44 may be selected as
appropriate depending on the weight of the vibration isolation subject to
be placed on the movable plate 3.

[0025] The movable plate 3 is overlaid on the fixed plate 2 through the
intermediation of the two-dimensional guiding mechanism 4. The guiding
member 42 freely moves in the X direction relative to the fixed plate 2,
and further, the movable plate 3 freely moves in the Y direction relative
to the guiding member 42, with the result that the movable plate 3 is
freely movable in the X direction and in the Y direction relative to the
fixed plate 2. Accordingly, when vibrations act from the floor surface
onto the fixed plate 2 installed on the floor surface, the movable plate
3 may freely vibrate in the X direction and in the Y direction in a cycle
different from that of the fixed plate 2.

[0026]FIG. 2 is a plan view illustrating a state in which the fixed state
of the upper slidable block 44 with respect to the coupling plate 45 of
the guiding member 42 is released and the movable plate 3 is removed from
the fixed plate 2. The fixed plate 2 is manufactured by die casting using
an aluminum alloy, and has a square shape as illustrated in FIG. 2. Along
the four side edges surrounding the fixed plate 2, a flange portion 20 is
provided so as to increase the strength of the fixed plate 2. In the
flange portion 20, there are formed tapped holes 21 to be used for
coupling to another dumping vibration isolating table or an inertial mass
table when constructing a vibration isolating table unit to be described
later.

[0027] The fixed plate 2 includes a fixed base portion 22 of the lower
guiding rail, which is provided between a corner portion 2a and a corner
portion 2c situated diagonally, and the lower guiding rail 40 is arranged
on this fixed base portion 22. In other words, in FIG. 2, the diagonal
line connecting the corner portion 2a and the corner portion 2c matches
with the X direction. Further, on both sides of the lower guiding rail 40
laid on the fixed base portion 22, ribs 23 for reinforcing the fixed base
portion 22 are provided. The lower slidable block 43 is mounted onto the
lower guiding rail 40 so as to straddle the lower guiding rail 40, and is
freely reciprocable between the corner portion 2a and the corner portion
2c of the fixed plate 2. Note that, the coupling plate 45 is fixed onto
the lower slidable block 43, and hence in FIG. 2, the lower slidable
block 43 is illustrated by the broken lines.

[0028] Further, between corner portions 2b and 2d of the fixed plate 2
situated on the lateral side of the lower guiding rail 40 and the
coupling plate 45 fixed to the lower slidable block 43, a plurality of
elastic members 5 formed of coil springs are provided, respectively.
Those elastic members 5 are stretched so that their tensile force is
reduced most greatly when the lower slidable block 43 is set at the
center position of the fixed plate 2 (hereinafter, referred to as
"initial position").

[0029]FIG. 3 is a view illustrating a state in which the lower slidable
block 43 moves along the lower guiding rail 40 from the initial position
to the end portion of the lower guiding rail 40. When the lower slidable
block 43 moves in this manner from the initial position toward any one of
the end portions of the lower guiding rail 40, the tensile force of each
elastic member 5 increases, and therefore a force F for pulling the lower
slidable block 43 back to the initial position acts on the lower slidable
block 43. Therefore, when the lower block shifts from the initial
position, the lower block then vibrates in the X direction with the
initial position set as the center of the amplitude.

[0030] Note that, in the example illustrated in FIG. 2, the elastic
members 5 are arranged in pairs on both sides of the lower guiding rail
40, but the number of the elastic members 5 may be changed as appropriate
in consideration of the weight of the vibration isolation subject to be
placed on the movable plate 3, resistance to the movement of the lower
slidable block 43 relative to the lower guiding rail 40, and the like.

[0031] Meanwhile, a pair of X-directional circulation belts 6 are
connected to the coupling plate 45. In this embodiment, the X-directional
circulation belts 6 are timing belts provided with teeth at constant
intervals along the longitudinal direction. The fixed base portion 22 is
provided with driven rollers 60 corresponding to both longitudinal ends
of the lower guiding rail 40, and the X-directional circulation belts 6
are looped around those driven rollers 60. In other words, the
X-directional circulation belts 6 are each stretched while including a
path parallel to the lower guiding rail 40.

[0032] Further, rotary dampers 7 are fixed at the corner portions 2b and
2d of the fixed plate 2 situated on the lateral side of the lower guiding
rail 40. The X-directional circulation belts 6 are looped also around
rotationally driven members 70 provided to the rotary dampers 7,
respectively. Thus, the X-directional circulation belts 6 are each
stretched into a circular shape along a substantially triangular path on
the lateral side of the lower guiding rail 40. When the coupling plate 45
moves in the X direction together with the lower slidable block 43, the
X-directional circulation belts 6 connected to the coupling plate 45
circulate and move along the path, to thereby impart rotational motion to
the rotationally driven members 70 provided to the rotary dampers 7 in
accordance with the X-directional movement amount of the coupling plate
45.

[0033] The rotary dampers 7 each include a case fixed to the fixed plate 2
and having an action chamber filled with a viscous fluid, and a rotor
freely rotatable inside the action chamber of the case and coupled to the
rotationally driven member 70. When the rotor rotates relative to the
case, the shearing frictional force of the viscous fluid acts as
rotational resistance to the rotation, and thus the rotational resistance
is imparted to the rotationally driven member 70 coupled to the rotor.

[0034] The rotational resistance generated by the rotary damper 7 acts on
the circulatory movement of the X-directional circulation belt 6, and
eventually acts as a resistance force to the X-directional movement of
the lower slidable block 43. In other words, the X-directional vibrations
of the lower slidable block 43 are damped by the rotary damper 7.

[0035] Note that, as the rotary damper 7, one of various commercial rotary
dampers may be selected and used as appropriate depending on the required
resistance force as long as the rotary damper imparts resistance to the
rotation of the rotationally driven member 70. At this time, from the
viewpoint of housing the rotary damper 7 in the gap between the fixed
plate 2 and the movable plate 3 and maintaining a lower height of the
movable plate 3 relative to the floor surface, it is preferred that the
rotary damper 7 be low in height in the rotational axis direction.

[0036] Meanwhile, similarly to the above-mentioned fixed plate 2, the
movable plate 3 to be overlaid on the fixed plate 2 is manufactured by
die casting using an aluminum alloy, and has the same shape as the fixed
plate 2. Note that, as illustrated in FIG. 1, the movable plate 3 is
overlaid on the fixed plate 2 while being turned upside down.

[0037] The state of arrangement of the upper guiding rail 41 and the upper
slidable block 44 with respect to the movable plate 3 is identical with
the state of arrangement of the lower guiding rail 40 and the lower
slidable block 43 with respect to the fixed plate 2. Note that, the upper
guiding rail 41 is arranged along a direction orthogonal to the lower
guiding rail 40. Specifically, the upper guiding rail 41 is arranged
along the diagonal line connecting the corner portion 2b and the corner
portion 2d of the fixed plate 2 in FIG. 2, and this diagonal line matches
with the Y direction of the present invention.

[0038] Further, as illustrated in FIG. 1, the upper slidable block 44
mounted onto the upper guiding rail 41 is fixed to the coupling plate 45,
and is integrated with the lower slidable block 43 to construct the
guiding member 42. Accordingly, the movable plate 3 is freely movable in
the Y direction relative to the guiding member 42. Between the coupling
plate 45 and the movable plate 3, a plurality of elastic members 8 formed
of coil springs are provided. The state of arrangement of the elastic
members 8 with respect to the movable plate 3 is identical with the state
of arrangement of the elastic members 5 with respect to the fixed plate
2. Specifically, the elastic members 8 are stretched so that their
tensile force is reduced most greatly when the upper slidable block 44 is
set at the center position of the movable plate 3 (hereinafter, referred
to as "initial position"). Therefore, when the upper slidable block 44
moves from the initial position toward any one of the end portions along
the upper guiding rail 41, the tensile force of each elastic member 8
increases, and therefore the upper slidable block 44 is pulled back to
the initial position along the upper guiding rail 41. in other words, the
upper slidable block 44 vibrates in the Y direction with the initial
position set as the center.

[0039] Further, a pair of Y-directional circulation belts 9 are stretched
on the movable plate 3, and the Y-directional circulation belts 9 are
connected to the coupling plate 45. Further, rotary dampers 10 are
respectively fixed at a pair of corner portions of the movable plate 3
opposed across the upper guiding rail 41. Rotationally driven members 100
are fixed to rotors of the rotary dampers 10, and the Y-directional
circulation belts 9 are looped around the rotationally driven members
100, respectively. Therefore, when the upper slidable block 44 moves in
the Y direction along the upper guiding rail 41, the Y-directional
circulation belts 9 connected to the coupling plate 45 circulate and move
along a predetermined path, to thereby impart rotational motion to the
rotationally driven members 100 provided to the rotary dampers 10 in
accordance with the Y-directional movement amount of the coupling plate
45. Further, rotational resistance generated by each rotary damper 10
acts on the circulatory movement of the Y-directional circulation belt 9,
and eventually acts as a resistance force to the Y-directional movement
of the upper slidable block 44. In other words, the Y-directional
vibrations of the upper slidable block 44 are damped by the rotary damper
10.

[0040] The elastic members 8, the Y-directional circulation belts 9, and
the rotary dampers 10 are arranged on the movable plate totally in the
same manner as the elastic members 5, the X-directional circulation belts
6, and the rotary dampers 7 are arranged on the fixed plate. Note that,
the direction of arrangement of the upper guiding rail is orthogonal to
the direction of arrangement of the lower guiding rail, and hence the
rotary dampers 10 are arranged on the movable plate 3 correspondingly to
the corner portion 2a and the corner portion 2c of the fixed plate in
FIG. 2.

[0041] Note that, FIG. 1 is a sectional view obtained by cutting the
dumping vibration isolating table 1 along the line I-I of FIG. 2.
Therefore, FIG. 1 does not illustrate the rotary dampers 7 and the
elastic members 5 provided to the fixed plate 2, and as for the upper
guiding rail 41 arranged on the movable plate 3, FIG. 1 illustrates the
cross section thereof that is perpendicular to the longitudinal
direction.

[0042] Further, the dumping vibration isolating table 1 of this embodiment
structured as described above is to be used in such a manner that the
fixed plate 2 is installed on a floor surface of a building or a
transportation vehicle, whereas a vibration isolation subject such as a
precision apparatus and an art object is placed on the movable plate 3.

[0043] For example, when vibrations act on the floor surface due to
transportation, an earthquake, or the like, the vibrations of the floor
surface are propagated to the vibration isolation subject through the
intermediation of the fixed plate 2 and the movable plate 3, with the
result that the vibration isolation subject also vibrates. However, as
described above, the movable plate may freely vibrate in the X direction
and in the Y direction relative to the fixed plate, and the movable plate
3 may vibrate irrespective of the amplitude and cycle of the vibrations
of the fixed plate 2. Therefore, the movable plate 3 on which the
vibration isolation subject is placed is held in a state of being
isolated from the vibrations of the fixed plate 2, and may be swayed with
vibrations having a longer cycle than the vibrations of the floor surface
without any restriction of the vibrations of the floor surface.
Accordingly, it is possible to effectively prevent damage to the
vibration isolation subject due to the vibrations of the floor surface.

[0044] When the movable plate 3 vibrates in the X direction relative to
the fixed plate 2, the lower slidable block 43 and the coupling plate 45
reciprocate in the X direction along the lower guiding rail 40, and hence
the X-directional circulation belts 6 connected to the coupling plate 45
advance and retreat in response to the X-directional vibrations of the
movable plate 3, to thereby rotate the rotationally driven members 70.
The rotary dampers 7 provided to the fixed plate impart the rotational
resistance to the rotationally driven members 70, and hence the
rotational resistance acts as a force for holding the X-directional
reciprocating motion of the coupling plate 45 with pressure through the
intermediation of the X-directional circulation belts 6, with the result
that the X-directional vibrations of the movable plate 3 relative to the
fixed plate 2 are damped.

[0045] Further, when the movable plate 3 vibrates in a similar manner in
the Y direction relative to the fixed plate 2, the movable plate 3
reciprocates in the Y direction on the guiding member 42 together with
the upper guiding rail 41, and hence the Y-directional circulation belts
9 connected to the coupling plate 45 advance and retreat in response to
the Y-directional vibrations of the movable plate, to thereby rotate the
rotationally driven members 100. The rotary dampers 10 provided to the
movable plate 3 impart the rotational resistance to the rotationally
driven members 100, and hence the rotational resistance acts as a force
for holding the Y-directional reciprocating motion of the coupling plate
45 with pressure through the intermediation of the Y-directional
circulation belts 9, with the result that the Y-directional vibrations of
the movable plate 3 relative to the fixed plate 2 are damped.

[0046] In other words, when the movable plate 3 vibrates in the X
direction and in the Y direction relative to the fixed plate 2, the
vibrations are damped by the rotary dampers 7 provided to the fixed plate
2 and the rotary dampers 10 provided to the movable plate 3. When the
vibrations acting from the floor surface onto the fixed plate 2 cease, it
is possible to quickly cease the vibrations of the movable plate 3
relative to the fixed plate 2.

[0047] At this time, the rotary dampers 7 exert the force for holding the
X-directional movement of the movable plate 3 with pressure, whereas the
rotary dampers 10 exert the force for holding the Y-directional movement
of the movable plate 3 with pressure. Thus, the rotary dampers 7 and 10
exert a function of increasing the static rigidity of the movable plate 3
relative to the fixed plate 2. Therefore, the movable plate 3 does not
shift relative to the fixed plate 2 when the force only slightly acts on
the movable plate 3. Accordingly, it is possible to overcome the problem
in that the vibration isolation subject placed on the movable plate 3 is
swayed relative to the floor surface in response to the vibrations
slightly acting on the floor surface.

[0048] Further, the rotary damper that utilizes, as a damping force, the
shearing frictional force acting on the viscous fluid exerts a larger
damping force as the rotational speed of the rotor increases. Therefore,
during the period in which the movable plate 3 is vibrating relative to
the fixed plate 2, the damping force of the rotary damper 7 becomes the
maximum when the guiding member 42 passes through the initial position of
the lower guiding rail 40, and the damping force of the rotary damper 10
becomes the maximum when the guiding member 42 passes through the initial
position of the upper guiding rail 41. Thus, it is possible to quickly
cease the vibrations of the movable plate 3 by causing the damping force
of each of the rotary dampers 7 and 10 to effectively act on the
vibrations.

[0049] Further, in the dumping vibration isolating table 1 of this
embodiment, the X-directional circulation belts 6, the Y-directional
circulation belts 9, and the rotary dampers 7 and 10 are housed in the
gap between the fixed plate and the movable plate that are overlaid one
on top of the other through the intermediation of the guiding member 42,
and hence the dumping vibration isolating table 1 can be constructed with
its size reduced greatly.

[0050] Next, description is given of a vibration isolating table unit
obtained by combining the vibration isolating table with damping
mechanism of the present invention with a vibration isolating table with
inertial mass.

[0051] When vibrations having a large amplitude act from the floor surface
onto the fixed plate 2, the amplitude of the vibrations of the movable
plate 3 relative to the fixed plate 2 tends to increase in accordance
therewith. The increase in amplitude of the vibrations of the movable
plate 3 relative to the fixed plate 2 corresponds to an increase in
amounts of the X-directional and Y-directional movement of the movable
plate 3 relative to the fixed plate 2. Hence, in order to isolate the
vibration isolation subject from the vibrations of the floor surface, it
becomes necessary to ensure sufficient lengths of the lower guiding rail
40 and the upper guiding rail 41. However, when sufficient lengths are
set for the lower guiding rail 40 and the upper guiding rail 41, the
fixed plate 2 and the movable plate 3 are upsized by an amount
corresponding to the lengths thus set. As a result, for example, even in
a case where the vibration isolation subject to be placed on the movable
plate 3 is small in size, the dumping vibration isolating table 1 sized
suitably for this vibration isolation subject cannot be provided.
Further, there is a problem in that, when the amplitude of the vibrations
of the movable plate 3 relative to the fixed plate 2 is large, a large
allowance of space is necessary around the dumping vibration isolating
table 1 to avoid interference with the movable plate 3.

[0052] Thus, from the viewpoint of downsizing the dumping vibration
isolating table 1 while adapting the dumping vibration isolating table 1
to the input of large vibrations, it is conceived that a vibration
isolating table with inertial mass (hereinafter, referred to as "inertial
mass table") for reducing the amplitude of vibrations is used in
combination with the dumping vibration isolating table.

[0053] As a structure of the inertial mass table, there is conceived a
structure that directly employs the basic structure of the dumping
vibration isolating table 1 illustrated in FIG. 1, except that the rotary
dampers 7 and 10 respectively mounted onto the fixed plate and the
movable plate are replaced with inertial masses.

[0054]FIG. 4 is a plan view illustrating a structure of an inertial mass
table 11 that directly employs the structure of the dumping vibration
isolating table 1 illustrated in FIG. 1, and illustrates, similarly to
FIG. 2, a state in which the coupled state of the upper slidable block 44
with respect to the coupling plate 45 of the guiding member 42 is
released and the movable plate 3 is removed from the fixed plate 2. In
FIG. 4, reference numeral 12 represents an inertial mass, which is
provided in place of the rotary damper 7 of the dumping vibration
isolating table 1. The inertial mass 12 is a disc made of a metal and
having a uniform thickness, and the center of the inertial mass 12 is
borne so as to be freely rotatable relative to the fixed plate 2. In
addition, a pulley 13 serving as a rotationally driven member is fixed to
one end of the rotation shaft of the inertial mass 12. The X-directional
circulation belt 6 stretched on the fixed plate 2 is looped around the
pulley 13. The inertial mass 12 is formed to have a thickness smaller
than the height of the coupling plate 45 with respect to the fixed plate
2, and is housed in the gap between the fixed plate 2 and the movable
plate 3 when the movable plate 3 is overlaid on the fixed plate 2.

[0055] Note that, components other than the inertial mass 12 are the same
as those of the above-mentioned dumping vibration isolating table 1, and
therefore represented by the same reference symbols in FIG. 4 to omit
detailed description thereof.

[0056] Further, FIG. 4 illustrates only the structure in which components
are mounted onto the fixed plate 2, and the structure in which components
are mounted onto the movable plate 3 is totally the same as well.
Similarly to the dumping vibration isolating table 1, the vibration
control table 11 is completed by overlaying the movable plate 3 on the
fixed plate 2 through the intermediation of the guiding member 42.

[0057] As illustrated in FIG. 5, the inertial mass table 11 is used by
connecting the inertial mass table 11 to the above-mentioned dumping
vibration isolating table 1 to construct a vibration isolating table unit
15. At this time, the fixed plates and the movable plates of the dumping
vibration isolating table 1 and the inertial mass table 11 are coupled
together, respectively, and the movable plates of the dumping vibration
isolating table 1 and the inertial mass table 11 are integrated with each
other to vibrate in the X direction and in the Y direction relative to
the respective fixed plates. Note that, FIG. 5 illustrates a state in
which the fixed plate of the dumping vibration isolating table 1 and the
fixed plate of the inertial mass table 11 are coupled to each other.

[0058] For example, in the inertial mass table 11, when the movable plate
3 vibrates in the X direction relative to the fixed plate 2, the lower
slidable block 43 that constructs the guiding member 42 reciprocates in
the X direction along the lower guiding rail 40, and accordingly the
X-directional circulation belt 6 repeatedly inverts the rotational
direction of the inertial mass 12. In other words, the X-directional
movement of the movable plate 3 relative to the fixed plate 2 is
converted into rotational motion of the inertial mass 12, and accordingly
the amplitude of the X-directional vibrations of the movable plate 3
relative to the fixed plate 2 can be reduced.

[0059] Further, the same applies to the Y-directional vibrations of the
movable plate 3. When the movable plate 3 vibrates in the Y direction,
the inertial mass 12 provided so as to be freely rotatable relative to
the movable plate 3 repeatedly inverts its rotational direction, and the
Y-directional movement of the movable plate 3 relative to the fixed plate
2 is converted into rotational motion of the inertial mass 12.
Accordingly, the amplitude of the Y-directional vibrations of the movable
plate 3 relative to the fixed plate 2 can be reduced.

[0060] That is, by coupling the inertial mass table 11 to the dumping
vibration isolating table 1, the amplitude of the vibrations of the
movable plate 3 relative to the fixed plate 2 can be reduced by the
vibration isolating table unit 15 as a whole. Thus, it is expected that
the vibration isolating table unit 15 itself be downsized and the
allowance of space around the vibration isolating table unit 15 be
reduced.

[0061] In FIG. 5, one inertial mass table 11 is coupled to one dumping
vibration isolating table 1 to construct the vibration isolating table
unit 15. However, the number of dumping vibration isolating tables 1 and
inertial mass tables 11 to be coupled together may be selected as
appropriate depending on the required size of the movable plate 3, the
weight of the vibration isolation subject to be placed on the movable
plate 3, and the like. That is, according to the vibration isolating
table unit 15 described above, by arbitrarily coupling the dumping
vibration isolating table 1 and the inertial mass table 11 to each other,
it is possible to freely construct the vibration isolating table unit 15
suitable for the size and weight of the vibration isolation subject, and
hence such a vibration isolating table unit 15 may flexibly support any
kinds of vibration isolation subjects.

[0062] Further, a vibration isolating table having no rotary dampers 7 and
10 or inertial mass 12, that is, a vibration isolating table in which the
movable plate 3 is simply borne on the fixed plate 2 through the
intermediation of the two-dimensional guiding mechanism 4 (hereinafter,
referred to as "basic vibration isolating table"), may be coupled to the
dumping vibration isolating table 1 and the inertial mass table 11 for
use.

[0063]FIG. 6 illustrates an example of the vibration isolating table unit
15 constructed by coupling together one dumping vibration isolating table
1, one inertial mass table 11, and two basic vibration isolating tables
16. In this manner, when an arbitrary number of dumping vibration
isolating tables 1, inertial mass tables 11, and basic vibration
isolating tables 16 are coupled together to construct the vibration
isolating table unit 15, it is possible to freely construct the vibration
isolating table unit 15 suitable for the size, weight, robustness, and
the like of the vibration isolation subject to be placed on the movable
plate, and to control the amplitude of vibrations occurring in the
movable plate and the damping characteristics of the vibrations.